The invention relates generally to mechanical devices installed on roadways to slow the speed of motor vehicles, and relates more particularly to an automatic speed bump that is operative based on the speed of the vehicle contacting the bump.
In the interest of safety to other vehicles and nearby pedestrians, the speed of motorized vehicles should be kept to a safe level. Excessive vehicular speeds, especially on roads through residential areas and in parking lots, create a dangerous environment for drivers and pedestrians alike. To that end, speed limits are posted on roads, with the local speed limit being dependent on the type of road and the location of the road. Unfortunately, many drivers disregard the posted speed limit.
Other methods, which drivers cannot disregard, are employed on some roads to keep the speed of vehicles at a safe level. It is common for speed bumps to be placed across roads in neighborhoods, parking lots, and other areas where it is desirable to ensure that vehicle speeds are limited. Such speed bumps are usually elongate, mounded areas of asphalt or cement that traverse the width of the road, or the width of a driving area of a parking lot, to ensure that each vehicle encounters the speed bump. The speed bumps are usually painted or physically treated in some manner to alert drivers to the presence of the speed bumps. The dimensions of the speed bumps are such that a vehicle must be slowed to a low speed to pass over the speed bump without jarring the vehicle. Passing over a speed bump at a higher speed, as is known to most drivers, causes a very undesirable jolt to the vehicle and its occupants. In this manner, speed bumps cause drivers to slow down to a low speed to pass over the bump.
Speed bumps are typically installed at intermittent locations along a road or parking lot, but close enough to each other so that vehicles traveling between adjacent speed bumps do not have enough linear road space to accelerate to an unsafe speed, considering the low speed to which the vehicle is slowed to pass over the speed bumps. The speed bumps can be spaced apart any desired distance, which usually depends on the type, shape, and location of the road. For example, speed bumps in a parking lot should be placed relatively close together to drastically limit the speed of vehicles to perhaps 10 mph, but speed bumps on a residential street can be placed further apart to limit the speed of vehicles to perhaps 20 mph or 30 mph. Therefore, speed bumps prevent vehicles from traveling at unsafe speeds along an expanse of a road, in a parking lot, or other driving area.
However, such speed bumps can be very inconvenient and frustrating because they do not discriminate between vehicles driving at different speeds. Speed bumps are installed to require drivers traveling too fast to slow to a low speed to pass over the speed bump. However, drivers that already are traveling at a safe speed do not need the added deterrent of the speed bump to maintain their vehicles at a safe speed. Therefore, although a speed bump is necessary to slow down a fast driver, the speed bump is not necessary, and is a nuisance, for the slower, safer driver who does not exceed the speed limit.
Therefore, speed bumps indiscriminately affect all drivers, even those traveling at a safe speed. This indiscriminate effect on vehicles traveling over speed bumps has caused many people to be opposed to the installation of speed bumps where they are otherwise needed, thereby contributing to an unsafe environment for other drivers on the road and nearby pedestrians.
Therefore, it can be seen that there is a need in the art for an automatic speed bump that is operative based on the speed of the vehicle that contacts the speed bump. There is also a need for an automatic speed bump that provides a bump for vehicles that encounter the speed bump traveling over a predetermined speed, but does not provide a bump for vehicles traveling below the predetermined speed. It is to the provision of such a speed bump that the present invention is primarily directed.
Briefly described, the present invention comprises a speed bump mounted on top of the pavement or recessed into the pavement. A front pivot member is hingedly connected to a base. The front pivot member is biased upwardly such that it is maintained at an inclined position in the absence of an external force acting upon it. The speed bump further comprises a speed-sensitive lock mechanism for locking the front pivot member in a raised position.
When a vehicle engages the speed bump at a speed that exceeds a predetermined speed, the impact of the tires on the speed bump causes the speed-sensitive lock mechanism to restrain the front pivot member in an inclined position. The inclined front pivot member thus provides a bump to a vehicle traveling above the predetermined speed. However, when the vehicle is traveling at a speed below the predetermined speed, the impact of the tires on the speed bump does not cause the speed-sensitive lock mechanism to restrain the front pivot member in an inclined position. Instead, the front pivot member collapses to a horizontal position such that the vehicle does not experience a bump.
Stated another way, in a preferred form the present invention comprises an automatic speed bump for use on a driving surface. The speed bump includes a base element mounted or recessed into the driving surface. A front pivot member is hingedly connected to the base plate and is biased towards an inclined, raised position by a spring. A speed-sensitive lock mechanism locks the front pivot member in a raised position when impacted by a vehicle tire traveling at a speed at or above the selected speed.
In a preferred form, the speed-sensitive lock mechanism comprises a lock member hingedly connected to the upper end of the front pivot member. The lock member has a lower end which rotates about the hinged connection. The lower end of the lock member is urged upwardly by a biasing means.
When a vehicle engages the speed bump at a speed that exceeds a predetermined speed, the impact of the tires on the speed bump causes the lock member to be driven downwardly rapidly enough, and with enough force, to force the lower end of the lock member into contact with the upper surface of the base plate. The lower end of the lock member is then restrained by the friction force between the lock member lower end and the upper surface of the base plate. This friction prevents any further rearward movement of the lock member, and therefore locks the front pivot member of the speed bump in an inclined position, thus providing a bump to the vehicle traveling above the predetermined speed.
However, when the vehicle is traveling at or below the predetermined speed, the force on the front pivot member causes the lock member to be driven downwardly to a lesser degree and more slowly as the lock member moves toward the base plate. The lower end of the lock member is not driven down hard enough to be restrained by the upper surface of the base plate. Instead, the biasing means urges the lower end of the lock member above the base plate. The lock member then slides along the top surface of the base plate. In this manner, the front pivot and lock members collapse to a horizontal position such that the vehicle does not experience a bump.
In a preferred form, the biasing means acting upon the lock member comprises a friction element moveably mounted to the lock member for movement between an extended and a retracted position. The friction element having a surface for slideable engagement with the upper surface of the base. A friction element biasing means is provided for biasing the friction element in the extended position. In the extended position, the friction element maintains the lower end of the lock element above the upper surface of the base plate. In the retracted position, the lower end of the lock member may contact the base plate.
In another preferred form, the biasing means acting upon the lock member comprises a friction element moveably mounted to the base for movement between an extended position and a retracted position. The friction element has a surface for slideable engagement with the lower end of the lock member. A friction element baising means is provided for biasing the friction element in the extended position. The lock mechanism further comprises a striker having a leading edge which can receive the lower end of the lock member. In the extended position, the leading edge of the strike plate is shrouded from contact by the lower end lock member. In the retracted position, the lower end of the lock member may be captured against the leading edge of the strike plate.
In another preferred form, the friction element can be replaced by other means, such as by a roller plate having spring-biased, telescoping rollers mounted thereon. Such a speed bump works essentially the same way as that described above. Namely, when a vehicle engages the speed bump above a predetermined speed, the roller plate becomes engaged with the strike plate and the vehicle experiences a hard bump. When the vehicle engages the speed bump below the predetermined speed, the roller plate smoothly rolls away, flattening the speed bump so that the vehicle does not experience a bump. The predetermined speed can be altered by changing the spring rate, length, and/or pre-load in the springs that bias the telescoping rollers. This arrangement is quieter in use and provides for longer life (due to rolling contact, rather than sliding contact).
The device may utilize a separate rear pivot member hingedly connected at its upper end to the front pivot member. The rear pivot member protects the lock member, friction element and friction element biasing means from impact by the tires of a vehicle approaching the speed bump from the rear. The lower end of the rear pivot member may rest upon the strike plate, or base plate, and in operation, will collapse to a horizontal position with the collapse of the front pivot and lock members. The lower end of the rear pivot member may be hingedly connected to a sliding member. The sliding member is restrained to move horizontally and substantially parallel to the base plate. The horizontal movement of the sliding member may be limited to control the range of motion of the front pivot member, lock member and rear pivot member.
In a further preferred form, the device includes one or more rear plates pivotally coupled to the front and/or rear plate, a lock plate pivotally coupled to the front and/or rear plate between the front and rear plates, and a sensor associated with the lock plate. The sensor can be provided by a spring-biased retractable support member that is coupled to and biased generally downward from the lock plate so that the support member can engage the base plate. Alternatively, the sensor can be provided by a spring-biased sensor rod extending from a rider member with a ramp and engaged by a lock pin extending from the lock plate. In a further alternative, the sensor can be provided by a spring-biased sensor rod extending from the lock plate and engaging a ramp attached to the base plate.
The present invention addresses the need in the art by providing a speed bump that automatically discriminates between vehicles traveling at different speeds. The invention does so by providing a bump to vehicles traveling above the predetermined speed, while not providing a bump to those vehicles traveling below the predetermined speed. The speed bump of the present invention is rugged, has few moving parts, and provides an inexpensive way to mechanically provide automatic operation of a speed bump based solely on the speed of a vehicle.
Accordingly, it is an object of the present invention to provide an automatic speed bump that is operative based on the speed of the vehicle that contacts the bump.
It is another object of the present invention to provide an automatic speed bump that provides a bump for vehicles traveling above a predetermined speed, but does not provide a bump for vehicles traveling below the predetermined speed.
It is another object of the present invention to provide an automatic speed bump that can be inexpensively constructed to mechanically provide automatic operation of a speed bump based on the speed of a vehicle. These and other objects, advantages, and features of the present invention will become apparent upon reading the following specification in conjunction with the accompanying drawing figures.